A Bad Argument?

  1. If nothing prevents x from existing, then x exists. (premise)
  2. Only something that exists can prevent x from existing. (premise)
  3. If x is prevented from existing, then x does not exist. (premise)
  4. If x prevents x from existing, then x exists. (By 2)
  5. If x prevents x from existing, then x does not exist. (By 3)
  6. Thus, nothing can prevent itself from existing. (By 4 and 5)
  7. Nothing distinct from God can prevent God from existing. (premise)
  8. Therefore, nothing can prevent God from existing. (By 6 and 7)
  9. Therefore, God exists. (By 1 and 8)

I don't know whose argument this is.